Fuze window assembly



Aug. 22, 1967 E. w. LANGEN ET AL 3,336,872-

FUZE WINDOW ASSEMBLY Filed Aug. 12. 1965 [in 31w:

INVENTORS EDWARD w. LANGEN RAYMONDF. LIMOGES ATTORNEY 3,336,872 FUZEWINDOW ASSEMBLY Edward W. Langen and Raymond F. Limoges, Rochester,

N.Y., assignors, by mesne assignments, to the United States of Americaas represented by the Secretary of the Navy Filed Aug. 12, 1965, Ser.No. 479,356 7 Claims. (Cl. 10270.2)

ABSTRACT OF THE DISCLOSURE A shield for a critical surface area of aprojectile or missile normally exposed to contaminants during launchcomprising a low melting point metal layer which is hard enough toresist surface damage during storage but readily melts due totemperature rise during flight and is then cast off. It is particularlyapplicable to infra-red fuze windows.

The present invention relates to projectile fuzes and more particularlyto a novel shield for the protection of critical surface area such asthe infrared windows commonly used in variable time fuzes.

Heretofore difliculty has been experienced in protecting windows used inthe fuzes of certain projectiles or missiles to prevent blinding thereofby deposits from the propellant gases to which the window is exposedduring projectile or missile launch. It will be apparent that theexistence of such deposits can interfere with or completely prevent theproper actuation of the fuze by rays trans mitted through the window andhence some means must be provided for preventing the deposit ofpropellant material thereon or for removing such material once it hasbeen deposited.

It has been proposed that a coating of wax or similar material could beapplied over the window which wax mixture would melt at the stagnationtemperature developed during the missile flight. The wax however, thougheffective when carefully applied and when not damaged during projectilehandling, has proved to be not suitable for production purposes.

Briefly the present invention provides window protection by positioningthereover a thin shield of a suitable metal which shield when exposed tothe very substantial temperatures developed during weapon flight willmelt and be wiped or thrown from its position in front of the windowassembly, aided by centrifugal spin forces.

An object of the present invention is to provide a device and method forprotecting critical areas such as the ray transmitting windows ofweapons against contamination during weapon storage or handling or fromthe propellant gases developed during weapon launching.

Another object is to provide a simple, light and inexpensive projectilewindow shield which is cheap, easy to apply and uniformly effective inoperation.

Another object is to provide a protective shielding device which mayreadily be applied during the normal window assembly process with aminimum interruption or interference with established assembly lineprocedures.

Still another object is to provide a window assembly protecting devicewhich remains fixed in place during weapon storage and handling andduring weapon launch but which is automatically removed by the normalenvironmental conditions encountered after launch.

Other objects, advantages, and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a vertical elevation partially in section of the forward tipof a projectile nose fuze illustrating one embodiment of the presentinvention;

} United States Patent 3,336,872 Patented Aug. 22, 1967 stainless steel,upon which is received a protective cover or shield in the form of adisk 17. Above all rests a retaining ring 18 which may be held in placeby an overturned flange portion 19 of the casing;

In the embodiment illustrated the inner surface of housing 10 is shownprovided with a second ledge 20 upon which rests the outer edge of thethin flat stainless steel washer 16. This ledge protects the windowassembly 12 from too much compressive force when the entire assembly iscompressed together and provides a solid abutment to receive thepressure which is applied to crimp over the flange 19.

The protective shield or disk 17 is formed of a metal alloy which has amelting point of 203 F. and the com position of which is 52.5% bismuth32.0% lead and 15.0% tin. A shield thickness of .0015 inch has beenfound preferable in the embodiment illustrated.

It will be apparent that the shield of this material will protect thewindow assembly from contamination during storage and handling andduring the initial weapon launch when it is most likely to becontaminated by propellant gases. Thereafter during the mid flight ofthe weapon the thin shield is rapidly heated by the air through which itpasses to attain a temperature in excess of its 203 F. melting point. Atsuch temperature the thin disk quickly disintegrates and spins to theoutside of the window assembly and is dissipated from the important raytransmitting surface thereof.

It will be obvious that there are several advantages to the constructionillustrated, particularly when the fuzes are being assembled byautomatic or semi-automatic machinery and it is a fairly simple matterto add the stainless steel washer and the protective metal disk beforethe retaining ring is secured in place.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

We claim:

1. In a fuze construction for an aerial weapon wherein a criticalsurface area must be protected from contamination by propellant gasesdeveloped during weapon launch the combination of:

a casing having a ledge for supporting a member with a critical surface;

a critical surface member supported on said ledge;

cushioning pads on opposite sides of the critical surface member;

said pads being disposed about the periphery of said critical surfacemember so as to leave the central area unobstructed; and

a protective shield of fusible material positioned over said criticalsurface said shield being fusible at temperatures normally generated byweapon flight.

2. The fuze construction of claim 1 wherein the parts are circular inform.

3. The fuze construction of claim 1 wherein a load distribution washerhaving an open area is located between the protective shield and thecritical area.

4. The fuze construction of claim 1 wherein the protective shield isformed of an alloy of bismuth, lead and tin.

5. The fuze construction of claim 1 wherein the protective shield isformed of an alloy of bismuth 52.5%, lead 32.0% and tin 15.5%.

6. The fuze construction of claim 1 wherein the protective shield isapproximately .0015" thick.

7. A fuze for an aerial Weapon comprising:

a casing having a central opening, said opening being bounded by aninwardly projecting ledge;

a critical surface assembly including a critical surface member locatedwithin said opening and resting on said ledge;

a second ledge Within said opening and spaced from the first ledge adistance to accommodate the critical surface assembly;

a flat washer with its outer portion resting on the second ledge and itsinner portion projecting inwardly 4 to overhang the periphery of thecritical surface assembly; a thin flat shield of metal overlying andprotecting said critical surface; said shield having a melting pointsubstantially below the temperature reached by the weapon in flight; anda retaining ring having an open central area and serving to retain theparts in close relationship.

References Cited UNITED STATES PATENTS 3,026,805 3/1962 Becker 10270.23,065,930 11/1962 Edelman 244-3.16 3,080,817 3/1963 Robinson et a1.102-925 3,113,521 12/1963 Waller 10292.5

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

20 W. C. ROCH, Assistant Examiner.

1. IN A FUZE CONSTRUCTION FOR AN AERIAL WEAPON WHEREIN A CIRITICALSURFACE AREA MUST BE PROTECTED FROM CONTAMINATION BY PROPELLANT GASESDEVELOPED DURING WEAPON LAUNCH THE COMBINATION OF: A CASING HAVING ALEDGE FOR SUPPORTING A MEMBER WITH A CRITICAL SURFACE; A CRITICALSURFACE MEMBER SUPPORTED ON SAID LEDGE; CUSHIONING PADS ON OPPOSITESIDES OF THE CRITICAL SURFACE MEMBER;